我正在使用com.hierynomus.smbj.share包；通过smb2连接到网络位置以检查其连接性，但这仅在我的活动开始时（在后台）运行。
我添加了一个侦听器，以在任务返回一个字符串值（失败，成功）后返回，一旦活动中的侦听器（我从中调用任务）被调用，然后我会创建一个Connection的新实例状态（循环）
这是我在活动的onCreate（）处检查连接的方式
//Global ConnectionStatus connectionStatus;
connectionStatus = new ConnectionStatus();
connectionStatus.setContext(this);
connectionStatus.setListener(this);
connectionStatus.setCon(databaseReadWrite.getMydbc());
connectionStatus.execute("CheckDatabase", "nodelay");
这是我试图在打开另一个活动时取消任务的方式
protected void onPause() {
delay.equals("cancel");
super.onPause();
MyApplication.activityPaused();
if (connectionStatus != null) {
connectionStatus.cancel(true);
}
hasRun = false;
}
然后，此任务在异步任务完成后在同一活动中运行，因此我重新运行了connectionStatus的新实例
@Override
public void onTaskCompleted(String result) {
ActionBar actionBar = this.getSupportActionBar();
String title = getTitle().toString();
String code = handlingFunctions.getResultCode(result);
if (code.equals("1")) {
Message.message(this, " Database connected to server!");
setTitle(title + result);
} else if (code.equals("2")) {
actionBar.setBackgroundDrawable(new ColorDrawable(Color.RED));
alertDialog.message(this, result);
} else if (code.equals("0")) {
actionBar.setBackgroundDrawable(new ColorDrawable(Color.RED));
setTitle(title + " Database connected in offline mode");
alertDialog.message(this, result);
} else if (code.equals("3")) {
//alertDialog.message(this, result);
imageStatus.setText(result);
} else if (code.equals("4")) {
imageStatus.setText(result);
}
connectionStatus = new ConnectionStatus();
connectionStatus.setContext(getApplicationContext());
connectionStatus.setListener(AllParts.this);
connectionStatus.setCon(databaseReadWrite.getMydbc());
connectionStatus.execute("CheckDatabase", "delay");
}
}
public class ConnectionStatus extends AsyncTask<String, Void, String> {
private OnConnectionStatusComplete listener;
private ArrayList<String> imageNames;
private ArrayList<ImageDetails> currentImageDetails;
private SQLiteConnection sqLiteConnection;
private Context context;
public void setListener(OnConnectionStatusComplete listen) {
this.listener = listen;
}
public void setImageNames(ArrayList<String> ImageNames) {
this.imageNames = ImageNames;
}
public void setCurrentDetails(ArrayList<ImageDetails> details) {
this.currentImageDetails = details;
}
@Override
protected void onPostExecute(String s) {
listener.onTaskCompleted(s);
}
public void setContext(Context mContext) {
context = mContext;
}
public void setCon(SQLiteConnection sqlite) {
sqLiteConnection = sqlite;
}
@Override
protected String doInBackground(String... strings) {
if(this.isCancelled()){
return "";
}else{
MyApplication myApplication = (MyApplication) context.getApplicationContext();
String IPAddress = myApplication.getIpaddress();
String domain = myApplication.getDomainname();
String username = myApplication.getUsername();
String password = myApplication.getPassword();
String containingFolder = myApplication.getSharefolder();
String temp = "";
//return null;
if (strings[1].equals("delay")) {
try {
Thread.sleep(6000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
if (strings[0].equals("CheckDatabase")) {
temp = checkDatabaseConnect();
} else {
temp = checkImageConnection(IPAddress, domain, username, password, containingFolder);
}
return temp;
}
}
String checkDatabaseConnect() {
String statement = "PRAGMA sync_status";
JSONArray is_ready = new JSONArray();
try {
SQLiteStatement mystatement = null;
try {
mystatement = sqLiteConnection.prepareStatement(statement);
} catch (SQLException ex) {
try {
java.io.File path = new java.io.File("/sdcard/exports/logs");
SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
String currentDateTime = dateFormat.format(new Date()) + " ";
java.io.File myFile = new java.io.File(path, "DBCrashes.txt");
FileOutputStream fOut = new FileOutputStream(myFile, true);
OutputStreamWriter myOutWriter = new OutputStreamWriter(fOut);
myOutWriter.append("\n" +
"\r");
myOutWriter.append(currentDateTime + "Get pragma results: (" + statement + ")" + ex);
myOutWriter.close();
fOut.close();
} catch (java.io.IOException e) {
//do something if an IOException occurs.
}
}
mystatement.step();
int ncols = mystatement.getColumnCount();
if (ncols > 0) {
String result = mystatement.getColumnTextNativeString(0);
JSONObject jObject = new JSONObject(result);
is_ready = jObject.getJSONArray("peers");
if (is_ready.length() > 0) {
return "Success, Database is connected! (1)";
} else {
return "The database is not connected to the server. In offline mode, check network and restart application to connect to server. (0)";
}
}
mystatement.dispose();
} catch (SQLException ex) {
try {
java.io.File path = new java.io.File("/sdcard/exports/logs");
SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
String currentDateTime = dateFormat.format(new Date()) + " ";
java.io.File myFile = new java.io.File(path, "DBCrashes.txt");
FileOutputStream fOut = new FileOutputStream(myFile, true);
OutputStreamWriter myOutWriter = new OutputStreamWriter(fOut);
myOutWriter.append("\n" +
"\r");
myOutWriter.append(currentDateTime + " (" + statement + ")" + ex);
myOutWriter.close();
fOut.close();
return "No connection to a database, please try again (2)";
} catch (java.io.IOException e) {
//do something if an IOException occurs.
}
} catch (JSONException e) {
e.printStackTrace();
}
return "Success (5)";
}
}
我遇到的问题是离开活动后，任务仍在运行并返回此错误（我知道这一点，因为它考虑了延迟）
答案 0 :(得分：1)
您确实实现了isCanceled的处理，但是此实现只是开始。
您的当前流量是这样的：
您如何解决此问题？
最简单的方法是在调用checkDatabaseConnection或checkImageConnection之前检查它是否已取消。甚至在那些方法内部，也检查它是否被取消。
即使正确完成操作，您的Thread.sleep也可能导致onPause调用后6秒钟取消AsyncTask。
由于这样的原因，不再使用AsyncTask。 Threading还有其他更好的选择。
答案 1 :(得分：0)
尝试检查在Thread.sleep(6000)之后是否取消了任务，因此，即使在调用cancel时任务处于睡眠状态，完成后仍会返回。
if (strings[1].equals("delay")) {
try {
Thread.sleep(6000);
if(this.isCancelled()) {
return "";
}
} catch (InterruptedException e) {
e.printStackTrace();
}
/*if(this.isCancelled()) {
return "";
}*/
}